ASTRONOMICAL SEARCHES FOR NONBARYONIC DARK-MATTER

Astronomical methods of searching for light Goldstone bosons (axions a nd arions), which are candidates for dark matter, are briefly discusse d. Three processes for the coupling between axions and photons are con sidered: (a) the decay of axions into two photons; (b) the conversion of photons into axions in the magnetic fields of stars and interstella r and intergalactic media; (c) the inverse transformation of axions ge nerated inside the cores of stars. The intergalactic light of clusters of galaxies and the brightness of the night sky are good candidates f or searches for an emission line arising from the radiative decay of a xions. The results of observations made with the 6 m telescope of the Special Astrophysical Observatory do not provide any evidence for the exsitence of the hadronic axion decay line. The best upper limit for t he photon-axion coupling constant is derived from linear polarization observations of magnetic Ap stars.